1. Field of the Invention
The present invention relates to an ink cartridge for an ink-jet recording apparatus, having an ink pack that is formed of flexible material into a flat bag shape, and that is stored in a case forming an outer shell of the cartridge.
2. Description of the Related Art
In general, an ink-jet recording apparatus is equipped with an ink-jet recording head which is mounted on a carriage and moved in the widthwise direction of recording paper, and paper feed system for moving the recording paper in the direction orthogonal to the traveling direction of the recording head. On the basis of print data, ink droplets are ejected from the recording head, thus recording the data on the recording paper.
In order to effect a comparatively-high volume of printing, a recording apparatus of this type supplied for, for example, an office or business purpose, requires use of high-volume ink cartridges. To this end, there has been provided a recording apparatus, in which ink cartridges are fitted to a cartridge holder provided, for example, to an apparatus main body.
In the recording apparatus, for example, sub-tanks are disposed on the carriage having the recording head, and the respective sub-tanks are replenished with ink from corresponding ink cartridges by way of ink supply tubes. The sub-tanks, in turn, supply ink to the recording head.
Recently, growing demand exists for a large-size recording apparatus capable of effecting printing on larger-size paper, in which a carriage travels a longer scan distance. In order to improve throughput of such a recording apparatus, a larger number of nozzles are provided in a recording head.
Further, demand exists for a recording apparatus which sequentially supplies ink to the respective sub-tanks mounted on the carriage from corresponding ink cartridges while performing printing operation, in order to improve throughput, and which stably supplies ink from the respective sub-tanks to the recording head.
In such a recording apparatus, since the ink supply tubes are required to connect the ink cartridges to the sub-tanks corresponding to the types of ink, and since the carriage travels over a longer scan distance, the lengths of respective ink supply tubes inevitably increase.
Further, as mentioned above, a larger number of nozzles are provided in the recording head. Hence, such a recording apparatus encounters a technical problem of deficient ink supply to the sub-tanks because the recording head consumes a large quantity of ink, and an increase in the dynamic pressure (i.e., pressure loss) of ink is likely to occur within each of the ink supply tubes interconnecting the ink cartridges and the sub-tanks.
As one measure to prevent this technical problem, there may be employed, for example, a construction in which air pressure is applied to the ink cartridges to forcibly induce ink flows from the ink cartridges to the sub-tanks under air pressure. This construction makes it possible to supply a sufficient amount of ink to the sub-tanks.
Preferably, an ink cartridge to be used in the recording apparatus having the foregoing construction includes a hermitically sealed case constituting an outer shell, and an ink pack which is formed by flexible material, which stores ink therein and which is accommodated in the case.
The ink pack in the ink cartridge of such a construction is depressed under pressurized air applied to the inside of the case to discharge and supply ink toward the recording head mounted on the carriage.
In this case, the ink filled in the ink pack is diminished in the vicinity of the outlet port of the ink pack. In a case where the amount of remaining ink has become smaller, the center portions of the ink pack, for example, come into close contact with each other to hinder ink flow.
Accordingly, residual ink cannot reach the area in the vicinity of the ink outlet port of the ink pack. That is, the ink cartridge becomes unusable while a considerable amount of ink still remains in the ink pack.
Consequently, the user is required to bear higher operating costs in the long term. Further, even at the time of disposal of a cartridge, the load such as treatment of the residual ink or the like is required.
Such a phenomenon is likely to arise particularly in a construction in which an ink pack is pressurized by the pressurized air applied into a case of the ink cartridge.